1. Field of the Invention
The present invention relates to a point specifying method and system, and a map displaying method and system using the same.
2. Description of Related Art
In prior art car navigation, the latitude and longitude of a point are typically input to specify the point. Japanese Patent Publication No. Hei 7-60479, however, discloses a system in which a map database is further stored as well as its corresponding relationships with a telephone number or address and a building so that the point is specified by inputting the telephone number.
Also, Japanese Patent Laid-Open No. Hei 6-88735 discloses a system in which individual registration numbers are assigned to the points (e.g., the intersections, the road starting points or arbitrary points between the intersections) so that the point is specified with the registration number.
However, the method of specifying the point with the latitude and longitude requires inputting two unknown parameters (the latitude and longitude) and has complicated inputting operations. Because of using the two unknown parameters, moreover, the specification of a position will be incorrect if the inputting order is wrong. Thus, this method is disadvantageous in that it has a poor operability.
On the other hand, the method of specifying the point with the telephone number or the address requires assembly of relationships among the telephone numbers, the buildings and the map into the database. This requirement raises a problem in that the point cannot be specified based on the latest information unless the database is always updated. In the method of specifying the point with the registration number, there is also a similar problem in that the database has to be updated if a new road is made.